Matching under concurrent fixed-ratio variable-interval schedules of food presentation.
Fixed-ratio schedules nudge pigeons toward concurrent interval options beyond what reinforcement rate alone predicts.
01Research in Context
What this study did
Bacotti (1977) tested pigeons on two keys at once. One key needed a fixed number of pecks for food. The other key paid off after random time passed.
The birds could hop between keys any time. The team logged every peck and the seconds spent on each side.
What they found
Power curves fit the data well, but the birds leaned toward the time-based key. The fixed-ratio key pulled them away less than the math said it should.
In plain words, ratio work created a built-in tilt toward the easier interval side.
How this fits with other research
Garcia et al. (1973) saw the same FR-VI setup and said, "Count the pecks, not the minutes." Their birds matched reinforcement rate when they looked at responses only. Bacotti (1977) adds that even response counts still hide a small interval bias.
Hopkins et al. (1977) re-checked older VI-VI data the same year. They found undermatching: birds gave the richer side fewer responses than strict matching predicts. V’s FR-VI bias is a cousin of undermatching; both show organisms deviate from perfect equality.
McMillan et al. (1999) later used the FR bias in drug work. They ran concurrent FR-FR schedules and showed that dose-effect curves bent depending on how big the ratio was. The 1977 lab finding became a tool for applied pharmacology.
Why it matters
When you set up concurrent schedules for kids or staff, remember that ratio requirements quietly push behavior toward the time-based option. If you want equal responding, either sweeten the ratio side or accept the tilt and plan goals around it.
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02At a glance
03Original abstract
Four pigeons were exposed to concurrent fixed-ratio, variable-interval schedules of food presentation. The fixed-ratio requirement was either 25, 50, 75, or 100 responses, with the variable-interval schedule parameter held constant at 4 minutes. A delay time was imposed between a changeover from one schedule to the other and subsequent food availability. The delay time was varied at each ratio requirement over four values; no delay, 0-second delay, 1.5-second delay, and 5.0-second delay. As the fixed-ratio requirement or the delay time increased, a greater proportion of the total responses and time spent responding occurred under the variable-interval schedule relative to the proportion of food deliveries under that schedule. Neither relative overall response rate nor relative time spent responding equalled the relative frequency of food presentation, as would be predicted by a linear "matching" model. Rather, these data were described by power functions with slopes of approximately 1.0 and intercepts greater than 1.0. In the terms of Baum's (1974) analysis, these deviations from linear matching represent bias in favor of responding under the interval schedule. Bias, as reflected in the intercept of the power function, was greater for the ratio of time than the ratio of responses.
Journal of the experimental analysis of behavior, 1977 · doi:10.1901/jeab.1977.27-171